Ketone Strips in 14 Seconds: Either They React or They Don't
This is a 14-second clip from 2017-07-19, the day after my day-three reply. It looks like the start of a strip explainer that stops after one idea. It's never been on YouTube (live JBTK4029).
In this recording
- [0:00] Ketone strips: here's how to use them. They either react or they don't, and if they react at all, that tells you ketones are there. In the clip I named the ketone as acetone (machine transcript).
That's the entire clip.
The line that holds up: read the strip as yes or no
The useful part is the framing. A strip is a yes-or-no test, not a score. My answer, even at 14 seconds, was: did it react? Then ketones are there. Stop there.
Two weeks later, in three ways to test for ketosis, I explained why the shade can mislead you. The strip measures what spills into urine. The more fat adapted you get, the less spills at the same level of ketosis, so the colour stops tracking your blood (video 8wOheKcBEd8). In are dark strips dangerous? I said a dark strip isn't, on its own, proof of dehydration (video GojQvo_2GS0). Both points come back to this clip: it reacted, so you're in. The shade is noise.
Correction: which ketone the strip sees
In this clip I said acetone. In the longer video two weeks later I said the strips pick up acetoacetate in the urine (video 8wOheKcBEd8). The machine transcript may have misheard me, or I may have said the wrong word. Either way, the later video is the one to go by.
Here's the background from the evidence pages. The liver makes three ketone bodies: acetoacetate, beta-hydroxybutyrate (BHB) and acetone (StatPearls, Ketogenesis). Laffel's widely cited review covers ketone levels in ketosis and in ketoacidosis, and how blood and urine ketone tests are used in diabetes (Laffel 1999). Blood meters read BHB. Breath meters read acetone. Urine strips, as I said in August, read what spills.
A note on safety
A positive strip on a diet isn't a warning sign by itself. But if you have type 1 diabetes, or type 2 and take insulin or other glucose-lowering drugs, ketone testing is a medical tool. A high reading with high blood sugar is a reason to call your doctor right away, not to post a photo of the strip. The difference is explained in ketosis vs ketoacidosis.
Then vs now
In 2017 I called urine strips a cheap test and the meters useful biofeedback, especially if you doubt you're in ketosis (video 8wOheKcBEd8). By 2019 I was telling people they didn't need a meter at all (video 1JbK1_ClDmY). Those two don't clash. A strip in your first weeks can reassure you that the change is happening. After that, how you feel, your appetite and your measurements tell you more.
Key points
- Read a urine strip as yes or no. Any reaction means ketones are present (live JBTK4029).
- Darkness doesn't track how "deep" you are, and it fades as you adapt (video 8wOheKcBEd8).
- I said acetone in this clip. My later video says urine strips detect acetoacetate.
- If you have diabetes and take insulin or glucose-lowering drugs, use ketone tests the way your doctor tells you to.